[{"data":1,"prerenderedAt":-1},["ShallowReactive",2],{"doc-seo-505131-105":3,"detail-sidebar-cat-0-en-105":81,"doc-detail-505131-en":130},{"code":4,"msg":5,"data":6},0,"ok",{"site_id":7,"language":8,"slug":9,"title":10,"keywords":11,"description":12,"schema_data":13,"social_meta":74,"head_meta":76,"extra_data":78,"updated_unix":80},105,"en","color-and-stellar-population-gradients-in-passively-evolving-galaxies-at-z-2-hstwfc3-deep-imaging-in-the-hubble-ultra-deep-field","Color and Stellar Population Gradients in Passively Evolving Galaxies at z ~ 2 - HST/WFC3 Deep Imaging in the Hubble Ultra Deep Field","","We detect color gradients in six massive, passively evolving galaxies at 1.3\u003Cz\u003C2.5 in the Hubble Ultra Deep Field using ultra-deep HST ACS and WFC3/IR imaging. After PSF matching, we build color maps and BVizYJH photometry in concentric annuli, from ~1.7 kpc to several H-band effective radii. Inner regions show redder rest-frame UV–optical colors than outer parts, with slopes largely independent of redshift and stellar mass, but correlated with dust obscuration E(B-V) and U-V. Single-parameter fits fail; stellar-population modeling indicates dust contributes, while age trends depend on metallicity gradients. The z~2 gradients are steeper than local early-type ones.",{"@graph":14,"@context":73},[15,34,56],{"@type":16,"itemListElement":17},"BreadcrumbList",[18,23,27,31],{"item":19,"name":20,"@type":21,"position":22},"https://docshare.wps.com","Home","ListItem",1,{"item":24,"name":25,"@type":21,"position":26},"https://docshare.wps.com/document/","Document",2,{"item":28,"name":29,"@type":21,"position":30},"https://docshare.wps.com/document/research-report/","Research & Report",3,{"item":32,"name":10,"@type":21,"position":33},"https://docshare.wps.com/document/color-and-stellar-population-gradients-in-passively-evolving-galaxies-at-z-2-hstwfc3-deep-imaging-in-the-hubble-ultra-deep-field/505131/",4,{"url":32,"name":10,"@type":35,"image":36,"author":41,"headline":10,"publisher":44,"fileFormat":47,"inLanguage":8,"description":12,"dateModified":48,"datePublished":49,"encodingFormat":47,"isAccessibleForFree":50,"interactionStatistic":51},"DigitalDocument",{"url":37,"@type":38,"width":39,"height":40},"https://docshare.wps.com/thumbnails/color-and-stellar-population-gradients-in-passively-evolving-galaxies-at-z-2-hstwfc3-deep-imaging-in-the-hubble-ultra-deep-field/505131.png","ImageObject",300,407,{"name":42,"@type":43},"Olivia Brown","Person",{"url":19,"name":45,"@type":46},"DocShare","Organization","application/pdf","2026-10-21","2026-10-04",true,{"@type":52,"interactionType":53,"userInteractionCount":55},"InteractionCounter",{"@type":54},"ViewAction",5,{"@type":57,"mainEntity":58},"FAQPage",[59,65,69],{"name":60,"@type":61,"acceptedAnswer":62},"What data and methods are used to measure the color gradients?","Question",{"text":63,"@type":64},"The study uses ultra-deep HST ACS and WFC3/IR images from the Hubble Ultra Deep Field. After matching PSFs, it derives color maps and multi-band BVizYJH photometry in concentric annuli.","Answer",{"name":66,"@type":61,"acceptedAnswer":67},"How do the inner and outer regions of these galaxies differ?",{"text":68,"@type":64},"Inner regions have redder rest-frame UV–optical colors (U-V, U-B, and B-V) than outer parts.",{"name":70,"@type":61,"acceptedAnswer":71},"What physical factors influence the gradient strength?",{"text":72,"@type":64},"The gradient slopes show no obvious dependence on redshift or stellar mass, but they mildly depend on dust obscuration E(B-V) and rest-frame (U-V) color; more obscured or redder galaxies have steeper gradients.","https://schema.org",{"og:url":32,"og:type":75,"og:title":10,"og:site_name":45,"og:description":12},"article",{"robots":77,"canonical":32},"index,follow",{"doc_id":79,"site_id":7},505131,1791137634,{"code":4,"msg":82,"data":83},"success",[84,88,92,96,100,105,110,114,119,122,126],{"id":22,"doc_module":4,"doc_module_name":25,"category_name":85,"show_sort_weight":86,"slug":87},"Story & Novel",90,"story-novel",{"id":26,"doc_module":4,"doc_module_name":25,"category_name":89,"show_sort_weight":90,"slug":91},"Literature",80,"literature",{"id":33,"doc_module":4,"doc_module_name":25,"category_name":93,"show_sort_weight":94,"slug":95},"Exam",70,"exam",{"id":55,"doc_module":4,"doc_module_name":25,"category_name":97,"show_sort_weight":98,"slug":99},"Comic",60,"comic",{"id":101,"doc_module":4,"doc_module_name":25,"category_name":102,"show_sort_weight":103,"slug":104},6,"Technology",50,"technology",{"id":106,"doc_module":4,"doc_module_name":25,"category_name":107,"show_sort_weight":108,"slug":109},7,"Healthcare",40,"healthcare",{"id":111,"doc_module":4,"doc_module_name":25,"category_name":29,"show_sort_weight":112,"slug":113},8,30,"research-report",{"id":115,"doc_module":4,"doc_module_name":25,"category_name":116,"show_sort_weight":117,"slug":118},9,"Religion & Spirituality",20,"religion-spirituality",{"id":117,"doc_module":4,"doc_module_name":25,"category_name":120,"show_sort_weight":117,"slug":121},"World Cup","world-cup",{"id":123,"doc_module":4,"doc_module_name":25,"category_name":124,"show_sort_weight":123,"slug":125},10,"Lifestyle","lifestyle",{"id":127,"doc_module":4,"doc_module_name":25,"category_name":128,"show_sort_weight":55,"slug":129},19,"General","general",{"code":4,"msg":82,"data":131},{"doc_id":79,"user_id":132,"nickname":42,"user_avatar":133,"doc_module":4,"category_id":111,"category_name":29,"doc_title":10,"doc_description":12,"doc_content":134,"file_id":135,"file_url":136,"file_type":137,"file_size":138,"view_count":55,"is_deleted":4,"is_public":22,"is_downloadable":22,"audit_status":22,"page_count":139,"language":140,"language_code":8,"site_id":7,"html_lang":8,"table_of_contents":141,"faqs":142,"seo_title":143,"seo_description":12,"update_tm":144,"read_time":145},16904993612988,"https://ap-avatar.wpscdn.com/davatar_a8503ba1806abce46bf441b54a3ca4cd","arXiv : 1101 .0843v2 [ astro-ph .CO] 5 May 2011  \nColor and Stellar Population Gradients in Passively Evolving Galaxies at z 􀀘 2 from HST/WFC3 Deep Imaging in the Hubble Ultra Deep Field  \nYicheng Guo1,2 , Mauro Giavalisco1 , Paolo Cassata1 , Henry C. Ferguson3 , Mark Dickinson4 , Alvio Renzini5 , Anton Koekemoer3 , Norman A. Grogin3 , Casey Papovich6 , Elena Tundo7 , Adriano Fontana8 ,  \nJennifer M. Lotz3 , Sara Salimbeni1  \n1 Astronomy Department, University of Massachusetts, 710 N. Pleasant Street, Amherst, MA 01003, U.S.A.  \n[2](2 email: yicheng@astro.umass.edu)[ email:](2 email: yicheng@astro.umass.edu)[ y](2 email: yicheng@astro.umass.edu)[icheng@astro.umass.edu](2 email: yicheng@astro.umass.edu)  \n3 Space Telescope Science Institute, 3700 San Martin Drive, Baltimore, MD, 21218, U.S.A.  \n4 NOAO-Tucson, 950 North Cherry Avenue, Tucson, AZ 85719, U.S.A.  \n5 INAF- Osservatorio Astronomico di Padova, Vicolo dell’Osservatorio 5, I-35122, Padova, Italy  \n6 George P. and Cynthia Woods Mitchell Institute for Fundamental Physics and Astronomy, Department of Physics, Texas A&M University, College Station, TX 77843-4242, U.S.A.  \n7 INAF- Osservatorio Astronomico di Trieste, Via Tiepolo 11, I-34131 Trieste, Italy  \n8 INAF- Osservatorio Astronomico di Roma, via Frascati 33, Monteporzio-Catone (Roma), I-00040, Italy  \nABSTRACT  \nWe report the detection of color gradients in six massive (stellar mass (Mstar) > 1010 M ⊙) and passively evolving (specific star formation rate (SSFR) \u003C 10−11yr −1) galaxies at redshift  \n1.3 \u003C z \u003C 2.5 identified in the Hubble Ultra Deep Field (HUDF) using ultra–deep HST ACSand WFC3/IR images. After carefully matching the different PSFs, we obtain color maps and multi–band optical/near–IR photometry (BVizYJH) in concentric annuli, from the smallest resolved radial distance (􀀙 1.7 kpc) up to several times the H–band effective radius. We find that the inner regions of these galaxies have redder rest-frame UV–optical colors (U-V, U-B and B-V) than the outer parts. The slopes ofthe color gradient have no obvious dependence on the redshift and on the stellar mass of the galaxies. They do mildly depend, however, on the overall dust obscuration (E(B-V)) and rest–frame (U-V) color, with more obscured or redder galaxies having steeper color gradients. The z 􀀘 2 color gradients are also steeper than those of local early–type ones. The gradient of a single parameter (age, extinction or metallicity) cannot fully explain the observed color gradients. Fitting the spatially resolved HST seven–band photometry to stellar population synthesis models, we find that, regardless of assumptions on the metallicity gradient, the redder inner regions of the galaxies have slightly higher dust obscuration than the bluer outer regions, implying that dust partly contributes to the observed color gradients, although the magnitude depends on the assumed extinction law. Due to the age–metallicity degeneracy, the derived age gradient depends on the assumptions for the metallicity gradient. We  \n– 2 –  \ndiscuss the implications of a number of assumptions for metallicity gradients on the formation and evolution of these galaxies. We find that the evolution of the mass–size relationship from z 􀀘 2 to the present cannot be driven by in–situ extended star formation, which implies that accretion or merger is mostly responsible for the growth of their stellar mass and size. The lack of a correlation between the strength of the color gradient and the stellar mass argues against the metallicity gradient predicted by the monolithic collapse scenario, which would require significant major mergers to evolve into the one observed at the present.  \nSubject headings: Cosmology: observations—Galaxies: evolution—Galaxies: formation—  \nGalaxies: high-redshift—Galaxies: stellar content—Galaxies: structure  \n1. Introduction  \nThe stellar mass (Mstar) of “spheroids”, namely elliptical galaxies and bulges of spiral galaxies, mostly consists of old stars that formed at h","cbCaiclDlhBDbEO6","https://ap.wps.com/l/cbCaiclDlhBDbEO6","pdf",1203157,39,"English","# Abstract\n# 1. Introduction\n## High-redshift spheroids and stellar populations\n## Evolution of massive passive galaxies and proposed mechanisms","[{\"question\":\"What data and methods are used to measure the color gradients?\",\"answer\":\"The study uses ultra-deep HST ACS and WFC3/IR images from the Hubble Ultra Deep Field. After matching PSFs, it derives color maps and multi-band BVizYJH photometry in concentric annuli.\"},{\"question\":\"How do the inner and outer regions of these galaxies differ?\",\"answer\":\"Inner regions have redder rest-frame UV–optical colors (U-V, U-B, and B-V) than outer parts.\"},{\"question\":\"What physical factors influence the gradient strength?\",\"answer\":\"The gradient slopes show no obvious dependence on redshift or stellar mass, but they mildly depend on dust obscuration E(B-V) and rest-frame (U-V) color; more obscured or redder galaxies have steeper gradients.\"}]","Color and Stellar Population Gradients in Passively Evolving Galaxies at z ~ 2 - HST/WFC3 Deep Imaging in the Hubble Ultra Deep Field | PDF",1791091388,98]